Copolymers with amphiphilic sub-units, a method for producing the same and the use thereof

ABSTRACT

The invention relates to a copolymer which can be obtained by radical copolymerisation of at least two components A and B. According to the invention, a) at least one ester of one at least difunctional carboxylic acid which has at least one olefinically unsaturated double bond is used with an alkyl oxide addition compound as component A and b) at least one additional monomer which can be subjected to radical polymerisation is used as component B. The invention also relates to a method for producing copolymers of this type and to the use thereof, in particular, to their use as a binding agent in adhesives.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Stage application filed under 35U.S.C. §371 of International Application No. PCT/EP00/03141, filed Apr.7, 2000, in the European Patent Office, claiming priority under 35U.S.C. §§119 and 365 of PCT/EP00/03141 and DE 199 17 356.7, filed onApr. 16, 1999, in the German Patent Office.

DESCRIPTION OF THE INVENTION

This invention relates to a copolymer obtainable by radicalcopolymerization of at least two components A and B,

a) at least one ester of an at least dibasic carboxylic acid containingat least one olefinically unsaturated double bond with at least onealkylene oxide adduct being used as component A and

b) at least one other radically polymerizable monomer being used ascomponent B.

The present invention also relates to a process for the production ofsuch copolymers and to their use, more particularly to their use inadhesives.

Properties of polymers are often adapted to meet certain technicalrequirements by the use of a mixture of monomers in the polymerizationprocess. The polymerization of a mixture of two or more monomers isoften referred to as copolymerization and leads, for example, tocopolymers containing two different types of monomer or to terpolymerscorresponding to the use of three different types of monomer. Inpolymers such as these, certain technical properties can often beestablished in dependence upon the comonomer ratio selected and thecomonomers selected.

Binders obtainable by radical polymerization of one or more radicallypolymerizable monomers are frequently used in the production of surfacecoatings or adhesives. Property variations are generally carried out bythe procedure mentioned above, i.e. by copolymerization of suitablemonomers.

It is known from the prior art that the flexibility of correspondingfilms, for example adhesive films, can be improved by the use ofcomonomers, such as dibutyl maleate, vinyl versatate or acrylates.Unfortunately, a disadvantage of using such comonomers is that theadhesion of such films or bonds to polar surfaces often deterioratessignificantly due to the hydrophobia of the comonomers. In addition,there is an upper limit to the chain length in the alcohol residues ofthe comonomers used to the extent that comonomers with long-chainresidues are not accessible to use in emulsion polymerization becausetheir solubility in water is too poor.

Emulsion polymerizations, for example the emulsion polymerization ofvinyl acetate, often require the addition of a protective colloid. Sucha process step on the one hand increases the duration of the processand, on the other hand, adds to the cost of the production.

Accordingly, the problem addressed by the present invention was toprovide a copolymer which could be produced without expensive processsteps and which, when used in adhesives, would lead to flexible adhesivefilms showing excellent adhesion even to hydrophilic substrate surfaces.Another problem addressed by the present invention was to provide aprocess for the production of that copolymer.

The problems stated above are solved by a copolymer obtainable by theradical copolymerization of at least two components A and B, component Abeing a carboxylic acid ester of an unsaturated carboxylic acid with analkylene oxide adduct and component B being another radicallypolymerizable monomer.

Accordingly, the present invention relates to a copolymer obtainable byradical copolymerization of at least two components A and B,

a) at least one ester of an at least dibasic carboxylic acid containingat least one olefinically unsaturated double bond with an alkylene oxideadduct being used as component A and

b) at least one other radically polymerizable monomer being used ascomponent B.

A “copolymer” in the context of the present specification is understoodto be a polymer obtainable by radical polymerization of two or moreradically polymerizable monomers. It may be a statistical copolymer,i.e. the sequence of monomers is not subject to any particular order, oreven an alternating or block copolymer.

According to the invention, a component A and a component B arecopolymerized to produce the copolymers according to the invention. Atleast one ester of an at least dibasic carboxylic acid containing atleast one olefinically unsaturated double bond with an alkylene oxideadduct is used as component A.

The at least dibasic carboxylic acid containing at least oneolefinically unsaturated double bond may be selected, for example, frommaleic acid, fumaric acid, itaconic acid, aconitic acid,3,4,5,6-tetrahydrophthalic acid, crotonic acid or a mixture of two ormore thereof.

Esters suitable for use as component A in accordance with the inventionmay be produced, for example, by only partly esterifying theolefinically unsaturated di- or polycarboxylic acids on which the estersare based, i.e. only some of the carboxylic acid groups available foresterification are esterified with a suitable alkylene oxide adduct. Inaddition, the carboxylic acid groups of the carboxylic acid may also bepartly or completely reacted with an alkylene oxide so that the esterfunction is formed by alkoxylation.

Partial esters suitable for use as component A in one preferredembodiment of the present invention are, for example, partial esters ofthe above-mentioned carboxylic acids with alkylene oxide adducts oflinear or branched saturated alcohols containing at least 8 carbonatoms. Suitable alcohols are, for example, the fatty alcohols containingat least 8 carbon atoms obtainable, for example, by reduction of naturalfats or oils or by reduction of fatty acids or fatty acids cutsobtainable from natural fats or oils or derivatives thereof, for exampleesters with alcohols containing 1 to 4 carbon atoms.

Fatty alcohols particularly suitable for the production of the alkyleneoxide adducts are, for example, octyl alcohol, nonyl alcohol, decylalcohol, undecyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecylalcohol, pentadecyl alcohol, hexadecyl alcohol, octadecyl alcohol,nonadecyl alcohol, Guerbet alcohols, unsaturated fatty alcohols, such as12-hydroxystearyl alcohol, or higher homologs of such alcoholscontaining up to about 44 carbon atoms. The alkyl residue of the fattyalcohols may be linear or branched, saturated or unsaturated.

Other suitable alcohol components for the production of the partialesters are, for example, alkylene oxide adducts of correspondinglyalkoxylatable compounds which have an OH group at the end of the alkoxyunit formed by the alkoxylation. Alkoxylatable compounds suitable forthe production of the alkylene oxide adducts are, for example,dialkylamines with linear or branched, saturated or unsaturated alkylchains containing a total of at least about 8 carbon atoms, linear orbranched, saturated or unsaturated carboxylic acids, for example fattyacids, containing at least about 8 carbon atoms, linear or branched,saturated or unsaturated acid amides, for example fatty acidmonoethanolamides, containing at least about 8 carbon atoms and linearor branched, saturated or unsaturated alkylamines; for example fattyamines, with at least 8 carbon atoms in the alkyl chain.

“Alkoxylates” or “alkylene oxide adducts” in the context of the presentspecification are understood to be the reaction products of suitablenucleophiles, for example correspondingly functionalized ethers, amines,carboxylic acids, carboxylic. acid amides or alcohols, with alkyleneoxides, containing 2 to about 44 carbon atoms, more particularly about 8to about 24 carbon atoms.

In one preferred embodiment of the invention, alkylene oxides containing2 to 4 and more particularly 2 or 3 carbon atoms, for example ethyleneoxide or propylene oxide, are used for the production of the alkyleneoxide adducts. Only one alkylene oxide need be used for the productionof the alkoxylation products, although two or more alkylene oxides mayalso be used. Where it is carried out with more than two alkyleneoxides, the alkoxylation can lead either to a statistical or analternating copolyalkylene oxide or to a block copolyalkylene oxide.

In one preferred embodiment of the invention, the alkoxylation by whichthe alkylene oxide adduct is formed is carried out with ethylene oxide.

The alkylene oxide adducts suitable for use as alcohol component inaccordance with the present invention contain on average at least onealkylene oxide unit per molecule. In a preferred embodiment of theinvention, the average number of alkylene oxide units per alcoholmolecule should be at least about 1.5 and, more particularly, at leastabout 2.

In another preferred embodiment of the invention, the partial esters ofolefinically unsaturated dicarboxylic acids which contain as theiralcohol residue an alkoxylate of an alcohol, a carboxylic acid, acarboxylic acid amide, a dialkyl amine or a monoalkoxylate of an amineare used as component A. In another preferred embodiment of theinvention, alkoxylates obtainable by alkoxylation of the compounds onwhich the alkoxylate is based with ethylene oxide or propylene oxide orboth are used as the alcohol residue.

In a preferred embodiment of the invention, the alcohol residues onwhich the partial esters are based have amphiphilic properties.Amphiphilic properties can often be:characterized by the HLB value ofthe amphiphilic compound.

Alcohol components suitable for the production of the partial esters inaccordance with the present invention have an HLB value of about 1.5 toabout 18, for example about 2 to about 14 or about 3 to about 12.

In a preferred embodiment of the invention, the nucleophile on which thealkylene oxide adduct is based contains about 12 to about 24 carbonatoms, for example about 16 to about 20 carbon atoms.

The corresponding alkylene oxide adducts contain about 1 to about 40alkylene oxide units, for example about 2 to about 12 ethylene oxide orpropylene oxide units or both.

The partial esters may be used in the form of their free acids althoughthey may also be used as salts, for example as alkali metal salts, orammonium salts. A preferred embodiment of the invention is characterizedby the use of partial ester salts with readily volatile amines, forexample salts with butylamine or triethanolamine. Salt formation may becarried out before or after the polymerization.

Besides the partial esters already described, esters of unsaturated atleast dibasic carboxylic acids with no carboxyl group (full esters),i.e. whose carboxyl groups are completely esterified, may be used ascomponent A in another embodiment of the invention.

Such full esters contain as their alcohol residue at least one alkyleneoxide adduct with a linear or branched, saturated or unsaturated alkylgroup containing at least about 8 carbon atoms which has at least 1 toabout 40 alkylene oxide units, for example about 2 to about 12 alkyleneoxide units, between the alkyl group mentioned and the ester functionemanating from the unsaturated carboxylic acid. Suitable alkylene oxideadducts were mentioned in the foregoing. In a preferred embodiment ofthe invention, the alkylene oxide units are ethylene oxide units orpropylene oxide units or a mixture thereof, but especially ethyleneoxide units.

An HLB value is a measure of the water or oil solubility ofpredominantly nonionic surfactants. For ethoxylates and their esters inparticular, the HLB value=(E+P)/5 where E is the number of ethyleneoxide units and P is the number of propylene oxide units (in % byweight) in the molecule. The HLB value of a surfactant or emulsifiermixture can be additively calculated from the values of itsconstituents. Detailed lists of HLB values of commercially availableemulsifiers can be found, for example, in Fiedler, Lexikon derHilfsstoffe für Pharmazie, Kosmetik oder angrenzende Gebiete or inKirk-Othmer (3.) 8, 910-918.

The production of the semiesters or full esters suitable for use ascomponent A is carried out under the standard rules of organic chemistryand is known to the expert. In a preferred embodiment of the invention,the semiester is formed from a carboxylic anhydride by addition of thecorresponding alkylene oxide adduct. If a semiester is to be used ascomponent A, the formation of the semiester may be carried out, forexample, in situ before or even during the copolymerization ofcomponents A and B by dissolving a corresponding carboxylic anhydrideand a corresponding alkylene oxide adduct or a mixture of two or morealkylene oxide adducts in component B introduced beforehand into thereactor.

According to the invention, at least one other radically polymerizablemonomer is used as component B. Suitable monomers are, for example, thevinyl esters of carboxylic acids containing about 2 to about 44 carbonatoms. Suitable vinyl esters are, for example, vinyl acetate, vinylpropionate, vinyl butyrate, the vinyl esters of the isomeric pentanoicacids, hexanoic acids, heptanoic acids, octanoic acids, nonanoic acids,decanoic acids and higher homologs thereof. Also suitable for use ascomponent B are, for example, acrylic acid, methacrylic acid, esters ofacrylic acid or methacrylic acid with linear or branched alcoholscontaining 1 to about 44 carbon atoms, styrene, ethylene, propylene,butylene, pentylene, hexylene and the higher homologous a-olefinscontaining up to about 18 carbon atoms or butadiene.

Suitable esters of acrylic or methacrylic acid are, in particular,methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate,tert.butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate,octyl acrylate, nonyl acrylate and the acrylic acid esters with thehigher homologs of the alcohols mentioned containing up to 44 carbonatoms, for example up to 18 carbon atoms. Suitable methacrylic acidesters are methyl methacrylate, ethyl methacrylate, propyl methacrylate,butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptylmethacrylate, octyl methacrylate, nonyl methacrylate or the methacrylicacid esters of the higher homologs of the above-mentioned alcoholscontaining up to about 44 carbon atoms, more particularly up to about 18carbon atoms.

In the copolymerization of components A and B, component A is present inthe polymerization mixture to be copolymerized in a quantity of about0.01 to 70% by weight, for example in a quantity of 0.5 to about 50% byweight or about 1 to about 20% by weight, based on the mixture as awhole. In another preferred embodiment of the invention, vinyl acetate,vinyl propionate, vinyl laurate or vinyl versatate, more especiallyvinyl acetate, is used as component B.

In another preferred embodiment of the invention, a mixture of two ormore copolymerizable monomers is used as component B. Suitable mixturesare, for example, mixtures of vinyl acetate, vinyl propionate, vinyllaurate or vinyl versatate with one or more of the other monomersmentioned above, more particularly with acrylic acid or methacrylic acidor the corresponding acrylic or methacrylic acid esters or a mixture oftwo or more of the compounds mentioned.

If mixtures of two or more monomers are used as component B, the mixturepreferably contains at least one vinyl ester of a carboxylic acid, moreparticularly vinyl acetate. The percentage content of vinyl ester of acarboxylic acid in such a mixture should be at least about 30% byweight.

The copolymers according to the invention may be produced by thestandard methods of radical polymerization. In a preferred embodiment ofthe invention, the polymerization is carried out as emulsion orsuspension polymerization in water. The polymerization temperature ispreferably about 50 to about 90° C. and more particularly about 75 toabout 85° C.

The emulsifiers used for the emulsion polymerization may be any of thosenormally used. A protective colloid may optionally be added.

Typical water-soluble radical initiators may be used as startermolecules, i.e. to initiate the radical polymerization. Lipophilicradical initiators may be added in the suspension polymerizationprocess.

Accordingly, the present invention also relates to a process for theproduction of a copolymer, characterized in that at least two componentsA and B are copolymerized,

a) at least one ester of an at least dibasic carboxylic acid containingat least one olefinically unsaturated double bond with an alkylene oxideadduct being used as component A and

b) at least one other radically polymerizable monomer being used ascomponent B.

The copolymers according to the invention are used, for example, inadhesive preparations, such as dispersion adhesives, pressure-sensitiveadhesives, in the production of adhesive films or for the production ofredispersion powders.

Accordingly, the present invention also relates to a preparation atleast containing 0.1% by weight of a copolymer according to theinvention or a copolymer produced by the process according to theinvention.

If alkylene oxide adducts containing olefinically unsaturated doublebonds are used for the production of component A, the preparationsaccording to the invention may additionally contain siccatives.

Besides the copolymers according to the invention, a preparationaccording to the invention may also contain up to about 50% by weight oftypical additives. Such additives can influence, for example, theadhesive properties, the aging behavior, the setting process oradhesion. For example, the adhesive may. contain so-called tackifierresins which may generally be divided into natural and synthetic resins.These include, for example, alkyd resins, epoxy resins, melamine resins,phenolic resins, urethane resins, hydrocarbon resins and natural resins,such as rosin, wood turpentine oil and tall oil. The synthetic resinsinclude hydrocarbon resins, ketone resins, coumarone-indene resins,isocyanate resins and terpene-phenol resins.

The adhesives according to the invention may also contain solvents.Suitable solvents are, for example, mono- or polyhydric alcoholscontaining about 2 to about 10 carbon atoms.

The adhesives according to the invention may also contain defoamers.Suitable defoamers are, for example, defoamers based on fatty alcoholsor silicone.

The adhesives may also contain protective colloids, such as polyvinylpyrrolidones, polyvinyl alcohols or cellulose or cellulose derivatives.

The adhesive according to the invention may also contain stabilizers orantioxidants as additives. Such additives generally include the phenols,for example sterically hindered high molecular weight phenols,polyhydric phenols, sulfur- and phosphorus-containing phenols or amines.Suitable stabilizers are, for example, hydroquinone, hydroquinone methylether, 2,3-(di-tert.butyl)-hydroquinone,1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert.butyl4-hydroxybenzyl)-benzene;pentaeryth ritol tetrakis-3-(3, 5-di-tert.butyl-4-hydroxyphenyl)-propionate;n-octadecyl-3,5-di-tert.butyl-4-hydroxyphenyl)-propionate;4,4-methylene-bis-(2,6-di-tert.butyl phenol);4,4-thiobis-(6-tert.butyl-o-cresol); 2,6-di-tert.butyl phenol;6-(4-hydroxyphenyoxy)-2,4-bis-(n-octylthio)-1,3,5-triazine;di-n-octadecyl-3,5-di-tert.butyl-4-hydroxybenzyl phosphonates;2-(n-octylthio)-ethyl-3,5-di-tert.butyl-4-hydroxybenzoate; sorbitolhexa-[3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate andp-hydroxydiphenylamine or N,N′-diphenylene diamine or phenothiazine.

The adhesive according to the invention may also contain plasticizers,such as benzoate plasticizers, phosphate plasticizers, liquid resinderivatives or vegetable and animal oils. Suitable plasticizers are, forexample, sucrose benzoate, diethylene glycol dibenzoate and/ordiethylene glycol benzoate, in which about 50 to about 95% of allhydroxyl groups have been esterified, phosphate plasticizers, forexample t-butyl phenyl diphenyl phosphate, polyethylene glycols andderivatives thereof, for example diphenyl ethers of poly(ethyleneglycol), liquid resin derivatives, for example the methyl ester ofhydrogenated resin, vegetable and animal oils, for example glycerolesters of fatty acids and polymerization products thereof.

Plasticizers based on phthalic acid, more particularly alkyl phthalates,are also suitable.

The adhesive according to the invention may also contain dyes, such astitanium dioxide, fillers, such as gypsum, talcum, clay and the like,and pigments.

The adhesives according to the invention may also contain emulsifiersand stabilizers or mixtures thereof. Suitable emulsifiers are,generally, surfactants containing a hydrophilic group and a hydrophobicgroup. These emulsifiers may be anionic emulsifiers, cationicemulsifiers or amphoteric emulsifiers. Other suitable emulsifiers are,for example, hydrocarbon emulsifiers containing about 6 to about 22carbon atoms where the hydrocarbon chain may be branched, unbranched,saturated, unsaturated, substituted, aliphatic or aromatic.

The present invention also relates to the use of a copolymer accordingto the invention or a copolymer produced by a process according to theinvention as binder in adhesive preparations, sealants, films or surfacecoating compositions.

The invention is illustrated by the following Examples.

EXPERIMENTAL PART Preparation of Maleic Acid/C_(12/14) Fatty Alcohol×4EO Semiester

367 g maleic anhydride (3.74 mol) and 800 g Dehydol LS 4 (C_(12/14)fatty alcohol×4 EO, 3.74 mol) are stirred under nitrogen for 3 hours at120° C. After cooling, 1 150 g of the semiester are obtained in the formof a paste. Acid value=139 mg KOH/g

EXAMPLE 1 Preparation of a Copolymer Dispersion of Vinyl Acetate andMaleic Acid C_(12/) ₁₄ Fatty Alcohol×4 EO Semiester

16 g of an initiator solution of 6 g potassium peroxodisulfate and 110 gwater are added with stirring to 862 g of a “preliminary”solution—heated to 75-80° C.—of 809 g deionized water, 1.8 g nonylphenolcontaining 9.5 mol EO, 20 g sulfosuccinic acid bis-2-ethyl hexyl estersodium salt, 1.4 g sodium hydrogen carbonate and 30 g partly saponifiedpolyvinyl alcohol. The remaining initiator solution (100 g) and themonomer solution consisting of 914 g vinyl acetate and 102 g of themaleic acid semiester are then added dropwise under reflux over a periodof 5 hours at that temperature (75-80° C.). It is important to ensurethat the temperature does not exceed 85° C. during the addition. Afterremoval of the coarse-particle constituents by filtration, ca. 1950 g ofa polymer dispersion with the following properties are obtained:

pH value: 2.5 to 3.5 solids: ca. 55% viscosity: 11,000 mPas.

EXAMPLE 2 Preparation of a Homopolymer Dispersion Containing VinylAcetate

10 g of an initiator solution of 4 g potassium peroxodisulfate and 76 gwater are added with stirring to 893.2 g of a “preliminary”solution—heated to 75-80° C.—of 799 g deionized water, 1.8 g nonylphenolcontaining 9.5 mol EO, 20 g sulfosuccinic acid bis-2-ethyl hexyl estersodium salt, 1.4 g sodium hydrogen carbonate and 71 g partly saponifiedpolyvinyl alcohol. The remaining initiator solution (70 g) and 816 gvinyl acetate are then added dropwise under reflux over a period of 5hours at that temperature (75-80° C.). It is important to ensure thatthe temperature does not exceed 85° C. during the addition. Afterremoval of the coarse-particle constituents by filtration, ca. 1760 g ofa polymer dispersion with the following properties are obtained:

pH value: 5.5 solids: ca. 51% viscosity: 9,000 mPas.

Comparison of the properties: Copolymer dispersion Homopolymerdispersion (Example 1) (Example 2) D1* 12 N/mm² 11.2 N/mm² Ultimatetensile stress 4.5 N/mm² 15 N/mm² Elongation at break 2200% 20 to 30% *=adhesive strength to European Standard 204, May 1991

What is claimed is:
 1. A copolymer consisting of the monomers: a) one ormore esters of one or more at least dibasic carboxylic acids having oneolefinically unsaturated double bond with one or more adducts of C₂₋₄₄alkylene oxides and one or more linear or branched, saturated fattyalcohols, dialkylamines, carboxylic acids, amides, or alkylaminescontaining 8 or more carbon atoms, said adducts containing 1 to 12alkylene oxide units; and b) one or more other radically polymerizablemonomers selected from the group consisting of vinyl esters of C₂₋₄₄carboxylic acids, acrylic acid, esters of acrylic acid or methacrylicacid with C₁₋₄₄ alcohols, and α-olefins containing up to 18 carbonatoms.
 2. The copolymer of claim 1, wherein a) comprises a partial estercomprising at least one carboxyl group.
 3. The copolymer of claim 1,wherein a) comprises an ester of one or more of maleic acid, fumaricacid, citraconic acid, itaconic acid, aconitic acid, and3,4,5,6-tetrahydrophthalic acid.
 4. The copolymer of claim 2, wherein a)comprises an ester of one or more of maleic acid, fumaric acid,citraconic acid, itaconic acid, aconitic acid, and3,4,5,6-tetrahydrophthalic acid.
 5. The copolymer of claim 1, wherein a)comprises at least one alkylene oxide adduct having an HLB value ofabout 2 to about
 20. 6. A process of making a copolymer comprising thesteps of: a) forming a reaction mixture of monomers consisting of one ormore esters of one or more at least dibasic carboxylic acids having oneolefinically unsaturated double bond with one or more adducts of C₂₋₄₄alkylene oxides and one or more linear or branched, saturated fattyalcohols, dialkylamines, carboxylic acids, amides, of alkylaminescontaining 8 or more carbon atoms, said adducts containing 1 to 12alkylene oxide units and one or more other radically polymerizablemonomers selected from the group consisting of vinyl esters of C₂₋₄₄carboxylic acids, acrylic acid, esters of acrylic acid or methacrylicacid with C₁₋₄₄ alcohols, and α-olefins containing up to 18 carbonatoms; and b) copolymerizing the monomers by radical polymerization. 7.The process of claim 6, wherein the reaction mixture comprises 0.1% to70% by weight of the one or more esters of the one or more at leastdibasic carboxylic acids having are olefinically unsaturated double bondwith the one or more alkylene oxide adducts.
 8. An adhesive, sealant,film, surface coating, or powder composition comprising as a binder atleast 0.1% by weight of the copolymer of claim
 1. 9. The copolymer ofclaim 1, wherein the one or more alkylene oxide adducts comprisereaction products of one or more fatty alcohols selected from the groupconsisting of octyl alcohol, nonyl alcohol, decyl alcohol, undecylalcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol,pentadecyl alcohol, hexadecyl alcohol, octadecyl alcohol, and nonadecylalcohol.
 10. The copolymer of claim 9, wherein the alkylene oxides have2 to 4 carbon atoms.
 11. The copolymer of claim 1, wherein a) comprisesat least one alkylene oxide adduct having an HLB value of about 1.5 toabout
 18. 12. The copolymer of claim 11, wherein a) comprises at leastone alkylene oxide adduct having an HLB value of about 2 to about 14.13. The copolymer of claim 12, wherein a) comprises at least onealkylene oxide adduct having an HLB value of about 3 to about
 12. 14.The copolymer of claim 1, wherein the alkylene oxide adducts have about1 to about 40 alkylene oxide units.
 15. The copolymer of claim 1,wherein the alkylene oxide adducts have about 2 to about 12 of one orboth of ethylene oxide or propylene oxide units.